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      in Environment

      Detailed images from space offer clearer picture of drought effects on plants

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      “MIT is a place where dreams come true,” says César Terrer, an assistant professor in the Department of Civil and Environmental Engineering. Here at MIT, Terrer says he’s given the resources needed to explore ideas he finds most exciting, and at the top of his list is climate science. In particular, he is interested in plant-soil interactions, and how the two can mitigate impacts of climate change. In 2022, Terrer received seed grant funding from the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) to produce drought monitoring systems for farmers. The project is leveraging a new generation of remote sensing devices to provide high-resolution plant water stress at regional to global scales.

      Growing up in Granada, Spain, Terrer always had an aptitude and passion for science. He studied environmental science at the University of Murcia, where he interned in the Department of Ecology. Using computational analysis tools, he worked on modeling species distribution in response to human development. Early on in his undergraduate experience, Terrer says he regarded his professors as “superheroes” with a kind of scholarly prowess. He knew he wanted to follow in their footsteps by one day working as a faculty member in academia. Of course, there would be many steps along the way before achieving that dream. 

      Upon completing his undergraduate studies, Terrer set his sights on exciting and adventurous research roles. He thought perhaps he would conduct field work in the Amazon, engaging with native communities. But when the opportunity arose to work in Australia on a state-of-the-art climate change experiment that simulates future levels of carbon dioxide, he headed south to study how plants react to CO2 in a biome of native Australian eucalyptus trees. It was during this experience that Terrer started to take a keen interest in the carbon cycle and the capacity of ecosystems to buffer rising levels of CO2 caused by human activity.

      Around 2014, he began to delve deeper into the carbon cycle as he began his doctoral studies at Imperial College London. The primary question Terrer sought to answer during his PhD was “will plants be able to absorb predicted future levels of CO2 in the atmosphere?” To answer the question, Terrer became an early adopter of artificial intelligence, machine learning, and remote sensing to analyze data from real-life, global climate change experiments. His findings from these “ground truth” values and observations resulted in a paper in the journal Science. In it, he claimed that climate models most likely overestimated how much carbon plants will be able to absorb by the end of the century, by a factor of three. 

      After postdoctoral positions at Stanford University and the Universitat Autonoma de Barcelona, followed by a prestigious Lawrence Fellowship, Terrer says he had “too many ideas and not enough time to accomplish all those ideas.” He knew it was time to lead his own group. Not long after applying for faculty positions, he landed at MIT. 

      New ways to monitor drought

      Terrer is employing similar methods to those he used during his PhD to analyze data from all over the world for his J-WAFS project. He and postdoc Wenzhe Jiao collect data from remote sensing satellites and field experiments and use machine learning to come up with new ways to monitor drought. Terrer says Jiao is a “remote sensing wizard,” who fuses data from different satellite products to understand the water cycle. With Jiao’s hydrology expertise and Terrer’s knowledge of plants, soil, and the carbon cycle, the duo is a formidable team to tackle this project.

      According to the U.N. World Meteorological Organization, the number and duration of droughts has increased by 29 percent since 2000, as compared to the two previous decades. From the Horn of Africa to the Western United States, drought is devastating vegetation and severely stressing water supplies, compromising food production and spiking food insecurity. Drought monitoring can offer fundamental information on drought location, frequency, and severity, but assessing the impact of drought on vegetation is extremely challenging. This is because plants’ sensitivity to water deficits varies across species and ecosystems. 

      Terrer and Jiao are able to obtain a clearer picture of how drought is affecting plants by employing the latest generation of remote sensing observations, which offer images of the planet with incredible spatial and temporal resolution. Satellite products such as Sentinel, Landsat, and Planet can provide daily images from space with such high resolution that individual trees can be discerned. Along with the images and datasets from satellites, the team is using ground-based observations from meteorological data. They are also using the MIT SuperCloud at MIT Lincoln Laboratory to process and analyze all of the data sets. The J-WAFS project is among one of the first to leverage high-resolution data to quantitatively measure plant drought impacts in the United States with the hopes of expanding to a global assessment in the future.

      Assisting farmers and resource managers 

      Every week, the U.S. Drought Monitor provides a map of drought conditions in the United States. The map has zero resolution and is more of a drought recap or summary, unable to predict future drought scenarios. The lack of a comprehensive spatiotemporal evaluation of historic and future drought impacts on global vegetation productivity is detrimental to farmers both in the United States and worldwide.  

      Terrer and Jiao plan to generate metrics for plant water stress at an unprecedented resolution of 10-30 meters. This means that they will be able to provide drought monitoring maps at the scale of a typical U.S. farm, giving farmers more precise, useful data every one to two days. The team will use the information from the satellites to monitor plant growth and soil moisture, as well as the time lag of plant growth response to soil moisture. In this way, Terrer and Jiao say they will eventually be able to create a kind of “plant water stress forecast” that may be able to predict adverse impacts of drought four weeks in advance. “According to the current soil moisture and lagged response time, we hope to predict plant water stress in the future,” says Jiao. 

      The expected outcomes of this project will give farmers, land and water resource managers, and decision-makers more accurate data at the farm-specific level, allowing for better drought preparation, mitigation, and adaptation. “We expect to make our data open-access online, after we finish the project, so that farmers and other stakeholders can use the maps as tools,” says Jiao. 

      Terrer adds that the project “has the potential to help us better understand the future states of climate systems, and also identify the regional hot spots more likely to experience water crises at the national, state, local, and tribal government scales.” He also expects the project will enhance our understanding of global carbon-water-energy cycle responses to drought, with applications in determining climate change impacts on natural ecosystems as a whole. More

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      Exploring the nanoworld of biogenic gems

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      A new research collaboration with The Bahrain Institute for Pearls and Gemstones (DANAT) will seek to develop advanced characterization tools for the analysis of the properties of pearls and to explore technologies to assign unique identifiers to individual pearls.

      The three-year project will be led by Admir Mašić, associate professor of civil and environmental engineering, in collaboration with Vladimir Bulović, the Fariborz Maseeh Chair in Emerging Technology and professor of electrical engineering and computer science.

      “Pearls are extremely complex and fascinating hierarchically ordered biological materials that are formed by a wide range of different species,” says Mašić. “Working with DANAT provides us a unique opportunity to apply our lab’s multi-scale materials characterization tools to identify potentially species-specific pearl fingerprints, while simultaneously addressing scientific research questions regarding the underlying biomineralization processes that could inform advances in sustainable building materials.”

      DANAT is a gemological laboratory specializing in the testing and study of natural pearls as a reflection of Bahrain’s pearling history and desire to protect and advance Bahrain’s pearling heritage. DANAT’s gemologists support clients and students through pearl, gemstone, and diamond identification services, as well as educational courses.

      Like many other precious gemstones, pearls have been human-made through scientific experimentation, says Noora Jamsheer, chief executive officer at DANAT. Over a century ago, cultured pearls entered markets as a competitive product to natural pearls, similar in appearance but different in value.

      “Gemological labs have been innovating scientific testing methods to differentiate between natural pearls and all other pearls that exist because of direct or indirect human intervention. Today the world knows natural pearls and cultured pearls. However, there are also pearls that fall in between these two categories,” says Jamsheer. “DANAT has the responsibility, as the leading gemological laboratory for pearl testing, to take the initiative necessary to ensure that testing methods keep pace with advances in the science of pearl cultivation.”

      Titled “Exploring the Nanoworld of Biogenic Gems,” the project will aim to improve the process of testing and identifying pearls by identifying morphological, micro-structural, optical, and chemical features sufficient to distinguish a pearl’s area of origin, method of growth, or both. MIT.nano, MIT’s open-access center for nanoscience and nanoengineering will be the organizational home for the project, where Mašić and his team will utilize the facility’s state-of-the-art characterization tools.

      In addition to discovering new methodologies for establishing a pearl’s origin, the project aims to utilize machine learning to automate pearl classification. Furthermore, researchers will investigate techniques to create a unique identifier associated with an individual pearl.

      The initial sponsored research project is expected to last three years, with potential for continued collaboration based on key findings or building upon the project’s success to open new avenues for research into the structure, properties, and growth of pearls. More

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      Low-cost device can measure air pollution anywhere

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      Air pollution is a major public health problem: The World Health Organization has estimated that it leads to over 4 million premature deaths worldwide annually. Still, it is not always extensively measured. But now an MIT research team is rolling out an open-source version of a low-cost, mobile pollution detector that could enable people to track air quality more widely.

      The detector, called Flatburn, can be made by 3D printing or by ordering inexpensive parts. The researchers have now tested and calibrated it in relation to existing state-of-the-art machines, and are publicly releasing all the information about it — how to build it, use it, and interpret the data.

      “The goal is for community groups or individual citizens anywhere to be able to measure local air pollution, identify its sources, and, ideally, create feedback loops with officials and stakeholders to create cleaner conditions,” says Carlo Ratti, director of MIT’s Senseable City Lab. 

      “We’ve been doing several pilots around the world, and we have refined a set of prototypes, with hardware, software, and protocols, to make sure the data we collect are robust from an environmental science point of view,” says Simone Mora, a research scientist at Senseable City Lab and co-author of a newly published paper detailing the scanner’s testing process. The Flatburn device is part of a larger project, known as City Scanner, using mobile devices to better understand urban life.

      “Hopefully with the release of the open-source Flatburn we can get grassroots groups, as well as communities in less developed countries, to follow our approach and build and share knowledge,” says An Wang, a researcher at Senseable City Lab and another of the paper’s co-authors.

      The paper, “Leveraging Machine Learning Algorithms to Advance Low-Cost Air Sensor Calibration in Stationary and Mobile Settings,” appears in the journal Atmospheric Environment.

      In addition to Wang, Mora, and Ratti the study’s authors are: Yuki Machida, a former research fellow at Senseable City Lab; Priyanka deSouza, an assistant professor of urban and regional planning at the University of Colorado at Denver; Tiffany Duhl, a researcher with the Massachusetts Department of Environmental Protection and a Tufts University research associate at the time of the project; Neelakshi Hudda, a research assistant professor at Tufts University; John L. Durant, a professor of civil and environmental engineering at Tufts University; and Fabio Duarte, principal research scientist at Senseable City Lab.

      The Flatburn concept at Senseable City Lab dates back to about 2017, when MIT researchers began prototyping a mobile pollution detector, originally to be deployed on garbage trucks in Cambridge, Massachusetts. The detectors are battery-powered and rechargable, either from power sources or a solar panel, with data stored on a card in the device that can be accessed remotely.

      The current extension of that project involved testing the devices in New York City and the Boston area, by seeing how they performed in comparison to already-working pollution detection systems. In New York, the researchers used 5 detectors to collect 1.6 million data points over four weeks in 2021, working with state officials to compare the results. In Boston, the team used mobile sensors, evaluating the Flatburn devices against a state-of-the-art system deployed by Tufts University along with a state agency.

      In both cases, the detectors were set up to measure concentrations of fine particulate matter as well as nitrogen dioxide, over an area of about 10 meters. Fine particular matter refers to tiny particles often associated with burning matter, from power plants, internal combustion engines in autos and fires, and more.

      The research team found that the mobile detectors estimated somewhat lower concentrations of fine particulate matter than the devices already in use, but with a strong enough correlation so that, with adjustments for weather conditions and other factors, the Flatburn devices can produce reliable results.

      “After following their deployment for a few months we can confidently say our low-cost monitors should behave the same way [as standard detectors],” Wang says. “We have a big vision, but we still have to make sure the data we collect is valid and can be used for regulatory and policy purposes,”

      Duarte adds: “If you follow these procedures with low-cost sensors you can still acquire good enough data to go back to [environmental] agencies with it, and say, ‘Let’s talk.’”

      The researchers did find that using the units in a mobile setting — on top of automobiles — means they will currently have an operating life of six months. They also identified a series of potential issues that people will have to deal with when using the Flatburn detectors generally. These include what the research team calls “drift,” the gradual changing of the detector’s readings over time, as well as “aging,” the more fundamental deterioration in a unit’s physical condition.

      Still, the researchers believe the units will function well, and they are providing complete instructions in their release of Flatburn as an open-source tool. That even includes guidance for working with officials, communities, and stakeholders to process the results and attempt to shape action.

      “It’s very important to engage with communities, to allow them to reflect on sources of pollution,” says Mora. 

      “The original idea of the project was to democratize environmental data, and that’s still the goal,” Duarte adds. “We want people to have the skills to analyze the data and engage with communities and officials.” More

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      Engaging enterprises with the climate crisis

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      Almost every large corporation is committed to achieving net zero carbon emissions by 2050 but lacks a roadmap to get there, says John Sterman, professor of management at MIT’s Sloan School of Management, co-director of the MIT Sloan Sustainability Initiative, and leader of its Climate Pathways Project. Sterman and colleagues offer a suite of well-honed strategies to smooth this journey, including a free global climate policy simulator called En-ROADS deployed in workshops that have educated more than 230,000 people, including thousands of senior elected officials and leaders in business and civil society around the world. 

      Running on ordinary laptops, En-ROADS examines how we can reduce carbon emissions to keep global warming under 2 degrees Celsius, Sterman says. Users, expert or not, can easily explore how dozens of policies, such as pricing carbon and electrifying vehicles, can affect hundreds of factors such as temperature, energy prices, and sea level rise. 

      En-ROADs and related work on climate change are just one thread in Sterman’s decades of research to integrate environmental sustainability with business decisions. 

      “There’s a fundamental alignment between a healthy environment, a healthy society, and a healthy economy,” he says. “Destroy the environment and you destroy the economy and society. Likewise, hungry, ill-housed, insecure people, lacking decent jobs and equity in opportunity, will catch the last fish and cut the last tree, destroying the environment and society. Unfortunately, a lot of businesses still see the issue as a trade-off — if we focus on the environment, it will hurt our bottom line; if we improve working conditions, it will raise our labor costs. That turns out not to be true in many, many cases. But how can we help people understand that fundamental alignment? That’s where simulation models can play a big role.”

      Play video

      Learning with management flight simulators 

      “My original field is system dynamics, a method for understanding the complex systems in which we’re embedded—whether those are organizations, companies, markets, society as a whole, or the climate system” Sterman says. “You can build these wonderful, complex simulation models that offer important insights and insight into high-leverage policies so that organizations can make significant improvements.” 

      “But those models don’t do any good at all unless the folks in those organizations can learn for themselves about what those high-leverage opportunities are,” he emphasizes. “You can show people the best scientific evidence, the best data, and it’s not necessarily going to change their minds about what they ought to be doing. You’ve got to create a process that helps smart but busy people learn how they can improve their organizations.” 

      Sterman and his colleagues pioneered management flight simulators — which, like aircraft flight simulators, offer an environment in which you can make decisions, seeing what works and what doesn’t, at low cost with no risk. 

      “People learn best from experience and experiment,” he points out. “But in many of the most important settings that we face today, experience comes too late to be useful, and experiments are impossible. In such settings, simulation becomes the only way people can learn for themselves and gain the confidence to change their behavior in the real world.” 

      “You can’t learn to fly a new jetliner by watching someone else; to learn, one must be at the controls,” Sterman emphasizes. “People don’t change deeply embedded beliefs and behaviors just because somebody tells them that what they’re doing is harmful and there are better options. People have to learn for themselves.”

      Play video

      Learning the business of sustainability 

      His longstanding “laboratory for sustainable business” course lets MIT Sloan School students learn the state of the art in sustainability challenges — not just climate change but microplastics, water shortages, toxins in our food and air, and other crises. As part of the course, students work in teams with organizations on real sustainability challenges. “We’ve had a very wide range of companies and other organizations participate, and many of them come back year after year,” Sterman says. 

      MIT Sloan also offers executive education in sustainability, in both open enrollment and customized programs. “We’ve had all kinds of folks, from all over the world and every industry” he says. 

      In his opening class for executive MBAs, he polls attendees to ask if sustainability is a material issue for their companies, and how actively those companies are addressing that issue. Almost all of the attendees agree that sustainability is a key issue, but nearly all say their companies are not doing enough, with many saying they “comply with all applicable laws and regulations.” 

      “So there’s a huge disconnect,” Sterman points out. “How do you close that gap? How do you take action? How do you break the idea that if you take action to be more sustainable it will hurt your business, when in fact it’s almost always the other way around? And then how can you make the change happen, so that what you’re doing will get implemented and stick?” 

      Simulating policies for sustainability 

      Management flight simulators that offer active learning can provide crucial guidance. In the case of climate change, En-ROADs presents a straightforward interface that lets users adjust sliders to experiment with actions to try to bring down carbon emissions. “Should we have a price on carbon?” Sterman asks. “Should we promote renewables? Should we work on methane? Stop deforestation? You can try anything you want. You get immediate feedback on the likely consequences of your decisions. Often people are surprised as favorite policies — say, planting trees — have only minor impact on global warming. (In the case of trees, because it takes so long for the trees to grow).”

      One En-ROADS alumnus works for a pharmaceutical company that set a target of zero net emissions by mid-century. But, as often observed, measures proposed at the senior corporate level were often resisted by the operating units. The alumnus attacked the problem by bringing workshops with simulations and other sustainability tools to front-line employees in a manufacturing plant he knew well. He asked these employees how they thought they could reduce carbon emissions and what they needed to do so. 

      “It turns out that they had a long list of opportunities to reduce the emissions from this plant,” Sterman says. “But they didn’t have any support to get it done. He helped their ideas get that support, get the resources, come up with ways to monitor their progress, and ways to look for quick wins. It’s been highly successful.” 

      En-ROADS helps people understand that process improvement activity takes resources; you might need to take some equipment offline temporarily, for example, to upgrade or improve it. “There’s a little bit of a worse-before-better trade-off,” he says. “You need to be prepared. The active learning, the use of the simulators, helps people prepare for that journey and overcome the barriers that they will face.” 

      Interactive workshops with En-ROADS and other sustainability tools also brought change to another large corporation, HSBC Bank U.S.A. Like many other financial institutions, HSBC has committed to significantly cut its emissions, but many employees and executives didn’t understand why or what that would entail. For instance, would the bank give up potential business in carbon-intensive industries? 

      Brought to more than 1,000 employees, the En-ROADS workshops let employees surface concerns they might have about continuing to be successful while addressing climate concerns. “It turns out in many cases, there isn’t that much of a trade-off,” Sterman remarks. “Fossil energy projects, for example, are extremely risky. And there are opportunities to improve margins in other businesses where you can help cut their carbon footprint.” 

      The free version of En-ROADS generally satisfies the needs of most organizations, but Sterman and his partners also can augment the model or develop customized workshops to address specific concerns. 

      People who take the workshops emerge with a greater understanding of climate change and its effects, and a deeper knowledge of the high-leverage opportunities to cut emissions. “Even more importantly, they come out with a greater sense of urgency,” he says. “But they also come out with an understanding that it’s not too late. Time is short, but what we do can still make a difference.”  More

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      Celebrating a decade of a more sustainable MIT, with a focus on the future

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      When MIT’s Office of Sustainability (MITOS) first launched in 2013, it was charged with integrating sustainability across all levels of campus by engaging the collective brainpower of students, staff, faculty, alumni, and partners. At the eighth annual Sustainability Connect, MITOS’s signature event, held nearly a decade later, the room was filled with MIT community members representing 67 different departments, labs, and centers — demonstrating the breadth of engagement across MIT.

      Held on Feb. 14 and hosting more than 100 staff, students, faculty, and researchers, the event was a forum on the future of sustainability leadership at MIT, designed to reflect on the work that had brought MIT to its present moment — focused on a net-zero future by 2026 and elimination of direct campus emissions by 2050 — and to plan forward.

      Director of Sustainability Julie Newman kicked off the day by reflecting on some of the questions that influenced the development of the MITOS framework, including: “How can MIT be a game-changing force for campus sustainability in the 21st century?” and “What are we solving for?” Newman shared that while these questions still drive the work of the office, considerations of the impact of this work have evolved. “We are becoming savvier at asking the follow-up question to these prompts,” she explained. “Are our solutions causing additional issues that we were remiss to ask, such as the impact on marginalized communities, unanticipated human health implications, and new forms of extraction?” Newman then encouraged attendees to think about these types of questions when envisioning and planning for the next decade of sustainability at MIT.

      While the event focused broadly on connecting the sustainability community at MIT, the day’s sessions tracked closely to the climate action plans that guided the office, 2015’s A Plan for Action on Climate Change and the current Fast Forward: MIT’s Climate Action Plan for the Decade. Both plans call for using the campus as a test bed, and at “A Model for Change: Field Reports from Campus as a Test Bed,” panelists Miho Mazereeuw, associate professor of architecture and urbanism, director of the Urban Risk Lab, and MITOS Faculty Fellow; Ken Strzepek, MITOS Faculty Fellow and research scientist at the MIT Center for Global Change Science; and Ippolyti Dellatolas graduate student and MITOS Climate Action Sustainability researcher shared ways in which they utilize the MIT campus as a test bed to design, study, and implement solutions related to flood risk, campus porosity, emissions reductions, and climate policy — efforts that can also inform work beyond MIT. Dellatolas reflected on success in this space. “With a successful campus as a test bed project, there is either output: we achieved these greenhouse gas emissions reductions or we learned something valuable in the process, so even if it fails, we understand why it failed and we can lend that knowledge to the next project,” she explained.

      Later in the morning, an “On the Horizon” panel focused on what key areas of focus, partnerships, and evolutions will propel the campus forward — anchored in the intersectional topics of decarbonization, climate justice, and experiential learning. To kick off the discussion, panelists John Fernández, director of the Environmental Solutions Initiative and professor of architecture; Joe Higgins, vice president for campus services and stewardship; Susy Jones, senior sustainability project manager; and Kate Trimble, senior associate dean for experiential learning shared which elements of their work have shifted in the last five years. Higgins commented on exciting progress being made in the space of renewables, electrification, smart thermostats, offshore wind, and other advances both at MIT and the municipal level. “You take this moment, and you think, these things weren’t in the moment five years ago when we were here on this stage. It brings a sense of abundance and optimism,” he concluded.

      Jones, for her part, shared how thinking about food and nutrition evolved over this period. “We’ve developed a lot of programming around nutrition. In the past few years, this new knowledge around the climate impact of our food system has joined the conversation,” she shared. “I think it’s really important to add that to the many years and decades of work that have been going on around food justice and food access and bring that climate conversation into that piece and acknowledge that, yes, the food system is accountable for about a quarter of global greenhouse gases.”

      Throughout the event, attendees were encouraged to share their questions and ideas for the future. In the closing workshop, “The Future of Sustainability at MIT,” attendees responded to questions such as, “What gives you hope?” and “What are we already doing well at MIT, what could we do more of?” The answers and ideas — which ranged from fusion to community co-design to a continued focus on justice — will inform MITOS’s work going forward, says Newman. “This is an activity we did within our core team, and the answers were so impactful and candid that we thought to bring it to the larger community to learn even more,” she says.

      That larger community was also recognized for their contributions with the first-ever Sustainability Awards, which honored nominated staff and students from departments across MIT for their contributions to building a more sustainable MIT. “This year we had a special opportunity to spotlight some of those individuals and teams leading transformative change at MIT,” explained Newman. “But everyone in the room and everyone working on sustainability at MIT in some way are our partners in this work. Our office could not do what we do without them.” More

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      Study: Smoke particles from wildfires can erode the ozone layer

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      A wildfire can pump smoke up into the stratosphere, where the particles drift for over a year. A new MIT study has found that while suspended there, these particles can trigger chemical reactions that erode the protective ozone layer shielding the Earth from the sun’s damaging ultraviolet radiation.

      The study, which appears today in Nature, focuses on the smoke from the “Black Summer” megafire in eastern Australia, which burned from December 2019 into January 2020. The fires — the country’s most devastating on record — scorched tens of millions of acres and pumped more than 1 million tons of smoke into the atmosphere.

      The MIT team identified a new chemical reaction by which smoke particles from the Australian wildfires made ozone depletion worse. By triggering this reaction, the fires likely contributed to a 3-5 percent depletion of total ozone at mid-latitudes in the Southern Hemisphere, in regions overlying Australia, New Zealand, and parts of Africa and South America.

      The researchers’ model also indicates the fires had an effect in the polar regions, eating away at the edges of the ozone hole over Antarctica. By late 2020, smoke particles from the Australian wildfires widened the Antarctic ozone hole by 2.5 million square kilometers — 10 percent of its area compared to the previous year.

      It’s unclear what long-term effect wildfires will have on ozone recovery. The United Nations recently reported that the ozone hole, and ozone depletion around the world, is on a recovery track, thanks to a sustained international effort to phase out ozone-depleting chemicals. But the MIT study suggests that as long as these chemicals persist in the atmosphere, large fires could spark a reaction that temporarily depletes ozone.

      “The Australian fires of 2020 were really a wake-up call for the science community,” says Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies at MIT and a leading climate scientist who first identified the chemicals responsible for the Antarctic ozone hole. “The effect of wildfires was not previously accounted for in [projections of] ozone recovery. And I think that effect may depend on whether fires become more frequent and intense as the planet warms.”

      The study is led by Solomon and MIT research scientist Kane Stone, along with collaborators from the Institute for Environmental and Climate Research in Guangzhou, China; the U.S. National Oceanic and Atmospheric Administration; the U.S. National Center for Atmospheric Research; and Colorado State University.

      Chlorine cascade

      The new study expands on a 2022 discovery by Solomon and her colleagues, in which they first identified a chemical link between wildfires and ozone depletion. The researchers found that chlorine-containing compounds, originally emitted by factories in the form of chlorofluorocarbons (CFCs), could react with the surface of fire aerosols. This interaction, they found, set off a chemical cascade that produced chlorine monoxide — the ultimate ozone-depleting molecule. Their results showed that the Australian wildfires likely depleted ozone through this newly identified chemical reaction.

      “But that didn’t explain all the changes that were observed in the stratosphere,” Solomon says. “There was a whole bunch of chlorine-related chemistry that was totally out of whack.”

      In the new study, the team took a closer look at the composition of molecules in the stratosphere following the Australian wildfires. They combed through three independent sets of satellite data and observed that in the months following the fires, concentrations of hydrochloric acid dropped significantly at mid-latitudes, while chlorine monoxide spiked.

      Hydrochloric acid (HCl) is present in the stratosphere as CFCs break down naturally over time. As long as chlorine is bound in the form of HCl, it doesn’t have a chance to destroy ozone. But if HCl breaks apart, chlorine can react with oxygen to form ozone-depleting chlorine monoxide.

      In the polar regions, HCl can break apart when it interacts with the surface of cloud particles at frigid temperatures of about 155 kelvins. However, this reaction was not expected to occur at mid-latitudes, where temperatures are much warmer.

      “The fact that HCl at mid-latitudes dropped by this unprecedented amount was to me kind of a danger signal,” Solomon says.

      She wondered: What if HCl could also interact with smoke particles, at warmer temperatures and in a way that released chlorine to destroy ozone? If such a reaction was possible, it would explain the imbalance of molecules and much of the ozone depletion observed following the Australian wildfires.

      Smoky drift

      Solomon and her colleagues dug through the chemical literature to see what sort of organic molecules could react with HCl at warmer temperatures to break it apart.

      “Lo and behold, I learned that HCl is extremely soluble in a whole broad range of organic species,” Solomon says. “It likes to glom on to lots of compounds.”

      The question then, was whether the Australian wildfires released any of those compounds that could have triggered HCl’s breakup and any subsequent depletion of ozone. When the team looked at the composition of smoke particles in the first days after the fires, the picture was anything but clear.

      “I looked at that stuff and threw up my hands and thought, there’s so much stuff in there, how am I ever going to figure this out?” Solomon recalls. “But then I realized it had actually taken some weeks before you saw the HCl drop, so you really need to look at the data on aged wildfire particles.”

      When the team expanded their search, they found that smoke particles persisted over months, circulating in the stratosphere at mid-latitudes, in the same regions and times when concentrations of HCl dropped.

      “It’s the aged smoke particles that really take up a lot of the HCl,” Solomon says. “And then you get, amazingly, the same reactions that you get in the ozone hole, but over mid-latitudes, at much warmer temperatures.”

      When the team incorporated this new chemical reaction into a model of atmospheric chemistry, and simulated the conditions of the Australian wildfires, they observed a 5 percent depletion of ozone throughout the stratosphere at mid-latitudes, and a 10 percent widening of the ozone hole over Antarctica.

      The reaction with HCl is likely the main pathway by which wildfires can deplete ozone. But Solomon guesses there may be other chlorine-containing compounds drifting in the stratosphere, that wildfires could unlock.

      “There’s now sort of a race against time,” Solomon says. “Hopefully, chlorine-containing compounds will have been destroyed, before the frequency of fires increases with climate change. This is all the more reason to be vigilant about global warming and these chlorine-containing compounds.”

      This research was supported, in part, by NASA and the U.S. National Science Foundation. More

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      Nanotube sensors are capable of detecting and distinguishing gibberellin plant hormones

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      Researchers from the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) interdisciplinary research group of the Singapore-MIT Alliance for Research and Technology (SMART), MIT’s research enterprise in Singapore, and their collaborators from Temasek Life Sciences Laboratory have developed the first-ever nanosensor that can detect and distinguish gibberellins (GAs), a class of hormones in plants that are important for growth. The novel nanosensors are nondestructive, unlike conventional collection methods, and have been successfully tested in living plants. Applied in the field for early-stage plant stress monitoring, the sensors could prove transformative for agriculture and plant biotechnology, giving farmers interested in high-tech precision agriculture and crop management a valuable tool to optimize yield.

      The researchers designed near-infrared fluorescent carbon nanotube sensors that are capable of detecting and distinguishing two plant hormones, GA3 and GA4. Belonging to a class of plant hormones known as gibberellins, GA3 and GA4 are diterpenoid phytohormones produced by plants that play an important role in modulating diverse processes involved in plant growth and development. GAs are thought to have played a role in the driving forces behind the “green revolution” of the 1960s, which was in turn credited with averting famine and saving the lives of many worldwide. The continued study of gibberellins could lead to further breakthroughs in agricultural science and have implications for food security.

      Climate change, global warming, and rising sea levels cause farming soil to get contaminated by saltwater, raising soil salinity. In turn, high soil salinity is known to negatively regulate GA biosynthesis and promote GA metabolism, resulting in the reduction of GA content in plants. The new nanosensors developed by the SMART researchers allow for the study of GA dynamics in living plants under salinity stress at a very early stage, potentially enabling farmers to make early interventions when eventually applied in the field. This forms the basis of early-stage stress detection.

      Currently, methods to detect GA3 and GA4 typically require mass spectroscopy-based analysis, a time-consuming and destructive process. In contrast, the new sensors developed by the researchers are highly selective for the respective GAs and offer real-time, in vivo monitoring of changes in GA levels across a broad range of plant species.

      Described in a paper titled “Near-Infrared Fluorescent Carbon Nanotube Sensors for the Plant Hormone Family Gibberellins” published in the journal Nano Letters, the research represents a breakthrough for early-stage plant stress detection and holds tremendous potential to advance plant biotechnology and agriculture. This paper builds on previous research by the team at SMART DiSTAP on single-walled carbon nanotube-based nanosensors using the corona phase molecular recognition (CoPhMoRe) platform.

      Based on the CoPhMoRe concept introduced by the lab of MIT Professor Professor Michael Strano, the novel sensors are able to detect GA kinetics in the roots of a variety of model and non-model plant species, including Arabidopsis, lettuce, and basil, as well as GA accumulation during lateral root emergence, highlighting the importance of GA in root system architecture. This was made possible by the researchers’ related development of a new coupled Raman/near infrared fluorimeter that enables self-referencing of nanosensor near infrared fluorescence with its Raman G-band, a new hardware innovation that removes the need for a separate reference nanosensor and greatly simplifies the instrumentation requirements by using a single optical channel to measure hormone concentration.

      Using the reversible GA nanosensors, the researchers detected increased endogenous GA levels in mutant plants producing greater amounts of GA20ox1, a key enzyme in GA biosynthesis, as well as decreased GA levels in plants under salinity stress. When exposed to salinity stress, researchers also found that lettuce growth was severely stunted — an indication that only became apparent after 10 days. In contrast, the GA nanosensors reported decreased GA levels after just six hours, demonstrating their efficacy as a much earlier indicator of salinity stress.

      “Our CoPhMoRe technique allows us to create nanoparticles that act like natural antibodies in that they can recognize and lock onto specific molecules. But they tend to be far more stable than alternatives. We have used this method to successfully create nanosensors for plant signals such as hydrogen peroxide and heavy-metal pollutants like arsenic in plants and soil,” says Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT who is co-corresponding author and DiSTAP co-lead principal investigator. “The method works to create sensors for organic molecules like synthetic auxin — an important plant hormone — as we have shown. This latest breakthrough now extends this success to a plant hormone family called gibberellins — an exceedingly difficult one to recognize.”

      Strano adds: “The resulting technology offers a rapid, real-time, and in vivo method to monitor changes in GA levels in virtually any plant, and can replace current sensing methods which are laborious, destructive, species-specific, and much less efficient.”

      Mervin Chun-Yi Ang, associate scientific director at DiSTAP and co-first author of the paper, says, “More than simply a breakthrough in plant stress detection, we have also demonstrated a hardware innovation in the form of a new coupled Raman/NIR fluorimeter that enabled self-referencing of SWNT sensor fluorescence with its Raman G-band, representing a major advance in the translation of our nanosensing tool sets to the field. In the near future, our sensors can be combined with low-cost electronics, portable optodes, or microneedle interfaces for industrial use, transforming how the industry screens for and mitigates plant stress in food crops and potentially improving growth and yield.”

      The new sensors could yet have a variety of industrial applications and use cases. Daisuke Urano, a Temasek Life Sciences Laboratory principal investigator, National University of Singapore (NUS) adjunct assistant professor, and co-corresponding author of the paper, explains, “GAs are known to regulate a wide range of plant development processes, from shoot, root, and flower development, to seed germination and plant stress responses. With the commercialization of GAs, these plant hormones are also sold to growers and farmers as plant growth regulators to promote plant growth and seed germination. Our novel GA nanosensors could be applied in the field for early-stage plant stress monitoring, and also be used by growers and farmers to track the uptake or metabolism of GA in their crops.”

      The design and development of the nanosensors, creation and validation of the coupled Raman/near infrared fluorimeter and related image/data processing algorithms, as well as statistical analysis of readouts from plant sensors for this study were performed by SMART and MIT. The Temasek Life Sciences Laboratory was responsible for the design, execution, and analysis of plant-related studies, including validation of nanosensors in living plants.

      This research was carried out by SMART and supported by the National Research Foundation of Singapore under its Campus for Research Excellence And Technological Enterprise (CREATE) program. The DiSTAP program, led by Strano and Singapore co-lead principal investigator Professor Chua Nam Hai, addresses deep problems in food production in Singapore and the world by developing a suite of impactful and novel analytical, genetic, and biomaterial technologies. The goal is to fundamentally change how plant biosynthetic pathways are discovered, monitored, engineered, and ultimately translated to meet the global demand for food and nutrients. Scientists from MIT, Temasek Life Sciences Laboratory, Nanyang Technological University (NTU) and NUS are collaboratively developing new tools for the continuous measurement of important plant metabolites and hormones for novel discovery, deeper understanding and control of plant biosynthetic pathways in ways not yet possible, especially in the context of green leafy vegetables; leveraging these new techniques to engineer plants with highly desirable properties for global food security, including high yield density production, and drought and pathogen resistance, and applying these technologies to improve urban farming.

      SMART was established by MIT and the National Research Foundation of Singapore in 2007. SMART serves as an intellectual and innovation hub for research interactions between MIT and Singapore, undertaking cutting-edge research projects in areas of interest to both Singapore and MIT. SMART currently comprises an Innovation Center and five interdisciplinary research groups: Antimicrobial Resistance, Critical Analytics for Manufacturing Personalized-Medicine, DiSTAP, Future Urban Mobility, and Low Energy Electronic Systems. More

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      in Environment

      Creating the steps to make organizational sustainability work

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      Sustainability is a hot topic. Companies throw around their carbon or recycling initiatives, and competing executives feel the need to follow suit. But aside from the external pressure, there are also bottom-line benefits. Becoming more efficient can save money. Creating a new product might make money; customers care about a company’s practices and will spend their money based on that.

      The work is in getting there, because becoming sustainable can seem simple: Establish a goal for five years down the road, and everything will fall into place — but it’s easy for things to get upended. “There is so much confusion and noise in this space,” says Jason Jay, senior lecturer and director of the Sustainability Initiative at MIT’s Sloan School of Management.

      His work is to help companies break through the confusion and figure out what they want to actually do, not merely what sounds good. It means doing research and listening to science. Mostly, it requires discipline, and because something new — be it a product, process or technology — is being asked for, it also takes ambition. “It’s a tricky dance,” he says, but one that can result in “doing well and doing good at the same time.”

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      It’s about taking steps

      Three steps, to be exact. The first, which is the crux, Jay says, is for a company to focus on a small set of issues that it can take the lead on. It sounds obvious, but it’s often missed. The problem is that companies will do either one of two things. They’ll take an outside-in approach in which they end up listening to too many stakeholders, “get pulled in a million different directions,” and try to solve all of society’s problems, which means solving none of them, he says.

      Or they’ll go inside-out and have one executive in charge of sustainability who will do some internal research and come up with an initiative. It might be a good idea, but it doesn’t take into account how it will affect the facilities, supply chains, and the people who work with them. And without that consideration, “It’s going to be very difficult to get the necessary traction inside the company,” Jay says.

      What’s needed is a combination of the two — outside perspectives coupled with insider knowledge — in order to find an initiative that resonates for that company. It starts with looking at what the company already does. That might show where it’s making a negative impact and, in turn, where it could make a positive one. It also involves the C-suite executives asking themselves, “What do we want this company to stand for?” and then, “What do I want my legacy to be?”

      Still, it can be hard to envision what change can look like or what actions might have an impact. Jay says this is where a simulation tool like En-ROADS, developed by MIT Sloan and Climate Interactive, can help explore scenarios.

      But it’s ultimately about making a commitment and allowing an iterative process to play out. A company then discovers its true focus might be something less flashy. Nike early on, for example, found that a huge source of greenhouse gas emissions was sulfur hexafluoride gas in the Nike Air bladder. When they re-engineered it, they ended up with inert nitrogen and a stronger material that was aesthetically cool and lightweight for the athlete. That didn’t come in one brainstorming meeting. It meant doing research and looking at what the science says is possible. It’s not quick, but it also shouldn’t be, if the goal is to take real, measurable action.

      “Cheap talk leads to cheap things,” Jay says. 

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      The next two

      Deciding what matters is key, but nothing materializes without establishing concrete goals. This is where a company “shows the world you’re serious.” But it’s a place where companies slip up. They either set weak goals, ones they know they can easily reach, so there’s no challenge, no accomplishment, “no stretch,” Jay says. Or they set goals that are too ambitious and/or aren’t backed by science. It could be, “We’re going to be net zero by 2050,” but how exactly is never answered.

      Jay says it’s about finding the sweet spot of having a reasonable amount of goals — like two to four — and then have those goals feel like a reach, yet possible. When that balance is right, it becomes a self-fulfilling prophecy. People stay motivated because they experience progress. But if it’s off, it won’t happen.

      “You need that optimal creative tension,” he says.

      And then there’s the third step. Companies need to find partners to make their sustainability programs succeed. It’s the one part that’s most overlooked because executives continually believe that they can do it alone. But they can’t, because big initiatives require help and expertise outside of a company’s realm.

      Maersk, the global shipping company, has a goal of replacing fossil fuel with green fuels for ocean freight, Jay says. It discovered that green ammonia could make that happen, and it was Yara, a fertilizer company, which best understood ammonia production. But it could also be a startup that’s working on a promising technology. Sometimes, as with moving to electric cars, what’s needed are political partners to enact policy and offer tax breaks and incentives. And it might be that the answer is collaborating with activists who have been pushing a company to change its ways.

      “There are strange bedfellows all around,” Jay says.

      Know how to tap the brake

      All the steps circle back to the essential point that becoming sustainable takes a committed investment of time, money, and patience. Starting small helps, especially in a corporate culture that tends to move slowly. Jay says there’s nothing wrong with going from zero projects to one, even if it’s a small one in a specific department. It allows people to become accustomed to the idea of change. It also lets the company establish a framework, analyze results, and build momentum, making it easier to ramp up.

      The patience part can be hard since there’s a rightful sense of urgency involved. Companies want to show that they’re doing something, and want to affect climate change sooner rather than later. But Jay likens it to building a skyscraper. The desire is to get it up fast, but if the foundation is shaky, everything will crumble.

      “What we’re trying to do is strengthen that foundation so it can reach the height we need,” he says. More